The invention concerns an arrangement for the jointed connection of a movable flow control element with a support element carrying it.
Arrangements of this type are found in many different fields of fluidics. The following are named examples:
1. Paper machine headbox in the flow channel of which a movable separating lamella is arranged or whose flow channel is limited by a movable control flap.
2. Airplane wings with movable flaps on the front or rear edges.
3. Rudder or adjustable hydrofoil on watercraft.
Known from the U.S. Pat. No. 4,617,091 is a paper machine headbox in the flow channel of which moveable separating lamellae are arranged. Each separating lamella features on its upstream end a bead (with predominantly round cross section) by which the separating lamella is pivotably mounted in a dovetail groove. This dovetail groove is provided on the downstream side of a perforated plate, also called flow grate. A jointed connection of that type has the disadvantage that gaps or slits exist in which dirt or fiber residue can accumulate. There is a risk that fiber accumulations separate now and then and proceed as lumps on the forming paper web, thereby adulterating the paper quality. Besides, there is the additional risk of increased friction and premature wear of the joint element.
According to U.S. Pat. No. 4,133,715, the separating lamella is subdivided in an upstream, highly elastic part and a downstream, less elastic part. The two parts, in turn, are connected with each other by a joint that has the same disadvantages as the aforementioned joint. A further disadvantage of this joint is constituted by forming in the flow control surfaces on both sides an unsteadiness which interferes with the flow.
The problem underlying the invention is to provide an arrangement for the jointed connection of a movable flow control element with a backing element where the gaps or slits (that may lead to dirt accumulations) are avoided. Additionally, the design of the arrangement is to be such that an undisturbed flow pattern will be assured.